snappyHexMesh/flange tutorial: remove the generated "flange" file.

tutorials/mesh/snappyHexMesh/flange/Allclean

@@ -5,7 +5,7 @@ cd ${0%/*} || exit 1    # run from this directory
 . $WM_PROJECT_DIR/bin/tools/CleanFunctions
 
 rm -rf 0 > /dev/null 2>&1
-rm -f ./*.obj > /dev/null 2>&1
+rm -f ./flange ./*.obj > /dev/null 2>&1
 rm -rf constant/extendedFeatureEdgeMesh > /dev/null 2>&1
 rm -f constant/triSurface/flange.eMesh > /dev/null 2>&1
 rm -f constant/polyMesh/boundary